PERF 8: How do you use tradeoffs to improve performance?

When architecting solutions, determining tradeoffs enables you to select an optimal approach. Often you can improve performance by trading consistency, durability, and space for time and latency.

Resources

Introducing The Amazon Builders’ Library (DOP328)
Amazon Builders’ Library
Best Practices for Implementing Amazon ElastiCache

Best Practices:

• Understand the areas where performance is most critical: Understand and identify areas where increasing the performance of your workload will have a positive impact on efficiency or customer experience. For example, a website that has a large amount of customer interaction can benefit from using edge services to move content delivery closer to customers.

• Learn about design patterns and services: Research and understand the various design patterns and services that help improve workload performance. As part of the analysis, identify what you could trade to achieve higher performance. For example, using a cache service can help to reduce the load placed on database systems; however, it requires some engineering to implement safe caching or possible introduction of eventual consistency in some areas.

• Identify how tradeoffs impact customers and efficiency: When evaluating performance-related improvements, determine which choices will impact your customers and workload efficiency. For example, if using a key-value data store increases system performance, it is important to evaluate how the eventually consistent nature of it will impact customers.

• Measure the impact of performance improvements: As changes are made to improve performance, evaluate the collected metrics and data. Use this information to determine impact that the performance improvement had on the workload, the workload’s components, and your customers. This measurement helps you understand the improvements that result from the tradeoff, and helps you determine if any negative side-effects were introduced.

• Use various performance-related strategies: Where applicable, utilize multiple strategies to improve performance. For example, using strategies like caching data to prevent excessive network or database calls, using read-replicas for database engines to improve read rates, sharding or compressing data where possible to reduce data volumes, and buffering and streaming of results as they are available to avoid blocking.

Improvement Plan

Understand the areas where performance is most critical

Identify constrained areas of the workload: Use load testing or monitoring to identify constrained areas (memory, CPU, custom metrics and other key performance indicators).

Learn about design patterns and services

Understand the available product options: Learn which performance configuration options are available and how they could impact the workload. Optimizing the performance of your workload depends on understanding how these options interact with your architecture, and the impact they have on measured performance and user-perceived performance.

Evaluate design patterns from the Amazon Builders’ Library: The Amazon Builders’ Library provides a detailed information about how Amazon builds and operates technology. The free articles in the library are written by Amazon’s senior engineers and cover topics across architecture, software delivery, and operations. For example, you can see how Amazon automates software delivery to achieve over 150 million deployments a year or how Amazon’s engineers implement principles such as shuffle sharding to build resilient systems that are highly available and fault tolerant.
Amazon Builders’ Library

Identify how tradeoffs impact customers and efficiency

Identify tradeoffs: Use metrics and monitoring to identify areas of poor performance in your system. Determine how to make improvements, and how tradeoffs will impact the system and the user experience. For example, implementing caching data can help dramatically improve performance, but it requires a clear strategy for how and when to update or invalidate cached data to prevent incorrect system behavior.

Measure the impact of performance improvements

Use a combination of strategies: A well-architected system uses a combination of performance related strategies. Determine which strategy will have the largest positive impact on a given hotspot or bottleneck. For example, sharding data across multiple relational database systems could improve overall throughput while retaining support for transactions and, within each shard, caching can help to reduce the load.

Use various performance-related strategies

Use a data-driven approach to evolve your architecture: As you make changes to the workload, collect and evaluate metrics to determine the impact of those changes. Measure the impacts to the system and to the end-user to understand how your tradeoffs impact your workload. Use a systematic approach, such as load testing, to explore whether the tradeoff improves performance.